1. Field of the Invention
The invention relates to a process for producing slabs, in particular from steel, in various formats in a stationary permanent mold, which has wide side walls and narrow side walls, of a continuous casting installation which,. To change the format, the pressure on the appropriate mold side walls is reduced and at least one of the mold walls is displaced into the desired position using appropriate pressure,. The invention further relates to a corresponding device for carrying out the process.
2. Discussion of the Prior Art
German reference DE-A 27 02 976 has disclosed a plate mold for the continuous casting of steel, in which the narrow side walls can be clamped securely between the wide side walls by means of a clamping fixture. In the adjustment range of the narrow side walls of this device, the wide side walls are arranged parallel to one another. Consequently, it is not possible to change the distance between the wide side walls and thus to change the format of the slab with the side walls installed.
Furthermore, European refference EP 0,658,387 A1 has disclosed a permanent mold for the continuous casting of steel strips, the wide side walls of which mold, at the side of a funnel-shaped charging area, are designed with inclined surfaces which move closer to one another toward the outside with respect to the narrow sides.
While in the former case the wide side walls maintain their distance from one another when the narrow side walls move, so that the distance between the rollers in the downstream strand guiding frame does not need to be adjusted, in the latter example the wide side walls move relative to one another in the event of an adjustment of the narrow side walls.
A drawback of the known solutions is that in the first case the slab thickness cannot be increased or reduced and in the second case the adjustment of the slab thickness can only be carried out by simultaneously changing the slab width, i.e. an adjustment of the thickness inevitably entails narrower or wider slabs.
In recognition of the above-mentioned drawbacks, the object of the invention is to provide a process and a corresponding device for producing slabs not only in any desired width but also in any desired thickness.
According to the invention, to change the format of the slab, the distances between the narrow side walls and consequently the width of the slab and/or the distances between the wide side walls and consequently the thickness of the slab are changed in any desired predeterminable manner. In an advantageous embodiment, the format is set in such a way that between two format changes the load on the strand shell is optimized by keeping the size approximately constant at the appropriate height of the permanent mold.
The continuous casting mold which is required to carry out the process is composed of in each case two wide side walls and two narrow side walls, the narrow side walls being composed of wedge-shaped parts. The narrow side walls comprise at least two wedge-shaped strips, the outer contact surfaces of which bear against the inner wall of the wide sides and the mutually facing contact surfaces of which run over the entire length of the individual parts.
The mutually facing contact surfaces are in this case guided in a plane which is substantially in the same direction as the corresponding wide side surfaces, facing toward one another with an angle of rotation xcex3 between 0 and 30xc2x0. The angular setting which differs from 0xc2x0 supports the pressure of the narrow side walls toward the wide side walls.
In an advantageous configuration, a tongue and a groove are provided at this location. The wedge angle xcex1 of the side surface parts is preferably selected between 3 and 6xc2x0. This angular range has proven sufficient to reliably set the desired thickness of the slab given appropriate vertical adjustment of one part of the narrow sides.
The narrow sides according to the invention which can be set for various slab thicknesses can be used not only with wide sides which are arranged with parallel walls within the narrow side adjustment range, but also with wide sides which are assigned to one another in a wedge shape in the narrow side adjustment range. In an advantageous configuration, a cone angle xcex2 of from 0.2xc2x0 to 2.5xc2x0 is provided here.
However, the adjustable narrow sides according to the invention can be used not only for vertical, stationary permanent molds, but also for molds of a bow-type continuous casting installation. In this embodiment, the wedge-shaped parts follow a constant radius on their mutually facing surfaces, the center of which radius differs from those of the individual wide side radii. During the paired adjustment movement of at least one of the corresponding narrow side parts, they are moved on an arc of a circle which follows the radius of the adjusted wide side.
In a further advantageous configuration, three parts are used per narrow side, in which case the middle wedge is designed symmetrically. In this case, the contact surfaces of the individual side parts may be arranged parallel to the wide side surfaces or conically with respect thereto. If a middle part of double-cone design is used, the side parts are jammed together particularly intimately. Secondly, this ensures that in the event of adjustment to the narrow sides the wide sides are not exposed to any movement whatsoever, or are exposed only to horizontal movement, in the adjustment range.
To achieve a horizontal movement of the narrow sides even without changing their thickness, it is proposed for a coupling to be arranged between the adjustment device and the movable wedge-shaped part.